Human hair keratin-associated proteins: Sequence regularities and structural implications

The study analyzed human keratin-associated proteins (KAP) and identified two fundamental pentapeptide quasi-repeats, A and B, with specific sequence patterns. These repeats were found in high-sulphur and ultra-high sulphur proteins, with some proteins containing predominantly A or B repeats. The research suggested that A repeats, with proline residues in the cis state, formed disulphide bond-stabilized structures, while B repeats offered more conformational flexibility. The study highlighted the potential role of KAP proteins in linking intermediate filaments (IF) and influencing the mechanical properties of keratin. The findings were based on sequence data from the human genome project and structural data from the PDB database.